THE CARBONIFEROUS LIMESTONE OF BURRINGTON COMBE 31 
Orthotetes aff. crenistria occurs abundantly throughout. 
Productus semireticulatus, in the typical form, occurs in 
this zone. In the higher part of the zone the mut. 
concinnus is abundant, attaining a maximum just below 
Horizon S. 
Productus ah. Cora (mut. C.) is not uncommon at the top 
of the zone. 
Chonetes cf. hardrensis occurs in the lower beds, but 
has yielded its predominance to Chonetes papilionacea, 
and dies out early in the zone. 
Chonetes papilionacea, which is abundant throughout 
the zone, crowds certain beds, and is at some levels asso- 
ciated with Chonetes cf. comoides in abundance. 
Rhipidomella ah. Michelini occurs rarely in the upper 
part of the zone. 
Corals. 
Caninia cylindrica, though never abundant, occurs 
throughout, and dies out at Horizon 
Zaphrentis ah. cornucopice has been recorded from the 
middle of the zone. 
Cyathophyllum (p first appears in the upper part of the 
main zone, but is not common below Horizon 
A Clisiophyllid has been found in the middle of this zone. 
The early occurrence of a member of this important group 
is very interesting ; particularly so because a similar 
specimen has been obtained by Dr. A. Vaughan from the 
same level in the Carboniferous Limestone of the Tenby 
district. 
Michelinia cf. megastoma is common throughout the 
zone, but has not been recorded at Horizon S. 
(in) Horizon 
This includes the beds extending from the corner below 
the cave to Plumley’s Den. 
